Purdue ECE Senior Design Semester Report
Course Number and Title
Semester / Year
Advisors
Team Number
Project Title
Name
Jay Zifer
Jamis Martin
TJ Andres
Brad Newark
ECE 477 Digital Systems Senior Design Project
Spring 2011
Prof. Meyer and Dr. Johnson
2
HOARD Robotics
Senior Design Students – Team Composition
Area(s) of Expertise
Major
Utilized in Project
CompE
Coding, Debugging
CompE
Micros, Coding, PBC
EE
Chassis, RF, Batteries
EE
Schematics, Coding
Expected
Graduation Date
May 2011
May 2011
December 2011
May 2011
Project Description: Provide a brief (2-3 page) technical description of the design project, as
outlined below:
(a) Summary of the project, including customer, purpose, specifications, and a summary of the
approach.
The goal of HOARD (Horde Of Autonomous Robotic Devices) is to develop a team of eight
robots that work together to accomplish tasks. Each robot is equipped with an array of six
IR LEDs and corresponding IR sensors for both object avoidance and proximity detection to
other robots. They are fitted with an RF module to enable wireless commands to be sent
from a main controller as well as communication between the robots. They also utilize two
ambient light sensors, which simulate chemical detection. The chemical detection mode
causes the robots to spread out and seek a chemical spill, which is simulated by a
concentrated bright light. When one robot finds the “chemical spill”, it then assists the other
robots to navigate towards it. This mode is practical for commercial use, such as detecting
chemical spills in a factory, or for military use. The second function is predator avoidance,
which is demonstrated in a “Humans vs. Zombies” mode. Initially, one human is infected
with a virus to turn it into a zombie. The humans then avoid the zombies, but are
transformed into one when caught. This mode is useful for predator vs. prey studies as well
as entertainment purposes. We approached this project with a “divide and conquer”
mentality. Large, complicated tasks are split up among simple robots that can cover a lot
more area and work together to accomplish tasks.
(b) Description of how the project built upon the knowledge and skills acquired in earlier ECE
coursework.
This project draws heavily on knowledge and skills we have learned in our ECE
coursework. On the basic level, we utilized skills from all the circuit design and analysis
classes for all the analog components. Our skills in microcontroller interfacing came directly
from ECE 362 and were used almost constantly. Our robots were coded in embedded C,
which we had experience with from ECE 362, but the knowledge of algorithms and the C
language came from ECE 264 and ECE 368. In order to communicate between robots, with
used an RF module. This required knowledge of serial communications, something we
experienced in ECE 337.
(c) Description of what new technical knowledge and skills, if any, were acquired in doing the
project.
Over the course of the semester, there are a number of new skills we had to develop for the
sake of our project. None of us had any experience with wireless communications prior to
this project, so it was necessary to do a lot of research and experimentation in order to
understand both the process of how to send and receive packets, and how to design our
own protocol. We had had little experience with PCB layouts, and spent a substantial
amount of time both learning the software and carefully planning how to best layout our
PCB. There was also a lot of battery management needed for this project that we had little
prior knowledge of. Finally, the fact that we built eight robots introduced a lot of mechanical
design challenges we had not previously faced with chassis design and working with
motors.
(d) Description of how the engineering design process was incorporated into the project.
Reference must be made to the following fundamental steps of the design process:
establishment of objectives and criteria, analysis, synthesis, construction, testing, and
evaluation.
Before the semester even began, our group had been meeting to talk about what we
wanted our project to be. The ideas drifted from a single robot with object recognition, to a
team of robots. From there, we eagerly began to set objectives for what we wanted our
robots to be able to do. We came up with a number of different programs, but settled that
there were two base functions that they should exhibit, a collective search, and collective
avoidance. From there, we examine what functionality the robots would need in order to
accomplish these behaviors. We would need to be able to communicate relative distance,
as well as information about the particular robot’s status. It was determined that IR and RF
synchronization would accomplish this well. The robots needed to be very agile and able to
turn in place, so a two wheel approach was decided on. All parts of the robot were
prototyped before committing to a design so that all testing was done before PCBs were
sent out. This also enabled us to create “heartbeat” programs for fast assembly and initial
software to be developed before the final product came in. Two final robots were then
analyzed and specific components evaluated before building the remaining robots.
(e) Summary of how realistic design constraints were incorporated into the project
(consideration of most of the following is required: economic, environmental, ethical,
health & safety, social, political, sustainability, and manufacturability constraints).
Economic: Most of the functionality of the robots is accomplished through the software.
This allowed for the robots to be individually simple and cost effective. This is especially
important because the functionality of HOARD robotics requires multiple robots, so the
overall cost has been kept to a minimum.
Environmental: With multiple robots needed for this project, environmental concerns were
taken into account not only for disposal, but also manufacturing. A simple aluminum chassis
was designed for fast manufacturing and ease of dismantling so it could be recycled after
project termination. Rechargeable NiMH batteries, which are better for the environment
than other rechargeable options, were used to cut down on the number of batteries thrown
away. Software was also written with energy conservation in mind so that the robots could
run as long as possible before having to charge again.
Ethical: Since one of the functions of the robots is to find a chemical spill, if they
malfunction and do not detect hazardous chemicals then people could get hurt. To ensure
proper function, every possible corner case we could think of was tested and addressed in
the software to get bugs out. If we are sending out a project that customers are relying on
for safety, then we needed to make sure it works in every scenario.
-2-
Health & Safety: HOARD robots are very small and have little potential of causing harm to
a user. Each robot is equipped with bright indication LEDs so that no one will accidentally
step on them. The battery has a three pin connector so that it cannot be plugged in
backwards and is placed on the bottom of the robot to protect the components and the user
if there are any complications. They are also designed to be remotely controlled so that
they can replace humans in hazardous situations.
Sustainability: The robots were built to last with time tested components and circuitry that
does not strain them to the limits. Also, if one robot is destroyed it has little effect on the
project goal. The horde was designed to be resilient towards adding and removing robots.
Manufacturability: Manufacturing of the robots was designed as a simple process. Once
the PCBs are manufactured, all that needs to be done is screw it onto the chassis, attach
the motors and battery, and plug in the RF module.
(f)
Description of the multidisciplinary nature of the project.
This project incorporates aspects of electrical engineering, computer engineering, and even
some mechanical engineering. The coding of the behaviors and the wireless
communications interfacing are both computer engineering skills. Our PCB layout as well
as the careful selection of parts and the design of our control unit involve electrical
engineering skills. The crafting of the chaises and the movement system were derived from
mechanical engineering.
(g) Description of project deliverables and their final status.
We are delivering eight robots, each complete with an RF communication module, IR LEDs
and IR sensors and ambient light sensors. Each robot’s mobility is accomplished by means
of two motors on the rear sides and a ball castor to balance on the front. The robots each
have three dip switches to assign roles in certain programs, a programming header,
indication LEDs, as well as a power switch. We are also delivering a handheld control
module with an LCD screen and control buttons. The control module is used to send
commands wirelessly to the robots such as start/stop and changing modes. The robots
have achieved all intended functionality, including the ability to avoid obstacles
autonomously, the ability to utilize swarm behavior to find a simulated chemical spill, and
the ability to utilize swarm behavior to avoid predators.
-3-